You might find your /24 routes filtered out at a lot of places that do have sensible route filtering But then yes, it'd protect you against the idiots who dont know bgp from a hole in the ground anyway and let whatever hijacking happen But I'd suggest do whatever such announcement if and only if you see a hijack, as a mitigation measure. On Thu, Aug 30, 2012 at 5:24 PM, Anurag Bhatia <me@anuragbhatia.com> wrote:
Hello everyone!
I tried looking on net but couldn't found direct answer, so thought to ask here for some advise.
Is using /24 a must to protect (a bit) against route hijacking? We all remember case of YouTube 2008 and hijacking in Pakistan. At that time YouTube was using /22 and thus /24 (more specific) announcement took almost all of Google's traffic even when AS path was long. So Google's direct also likely sent packets to Pakistan. Later Google too used /24 (and I guess /25 too to effect some region of internet). Similar case I remember for issue reported between Altus and hijacking by someone connected to Cleaveland exchange when ISP was using /23 and spammer used /24.
So can we conclude that one should always use /24 to make sure that they loose as little as possible traffic during prefix hijacking?
Also, if one uses /22 and /24 - will both prefixes will show in Global routing table? I know /24 will be prefered but will ISP see /22 as well or it will pop up only when /24 is filtered?
For one of IP's of Google.com, it seems it is coming from /16 and /24
http://bgp.he.net/ip/74.125.224.137
How can one print similar result from a route server like say Oregon route views or any ISP's server? I always /24 when looking for that IP. (in simple words - how bgp.he.net does this magic of popping both prefixes? I failed to do get same result from HE's route server)
Thanks!
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